About this replacement
Archos Neon 50b — 3.7V Li-ion Replacement Battery (AC50BNE)
This is a 3.7V, 2000mAh Li-ion replacement battery for the Archos Neon 50b smartphone. It fits both "Neon 50b" and "50b Neon" variants using OEM part number AC50BNE. Install it when the original cell no longer holds a usable charge through a normal day.
- Neon 50b and 50b Neon compatibility: Both model names refer to the same hardware platform. The PCB connector, cell dimensions (78.00 × 55.85 × 4.15mm), and BMS handshake are identical across both, so one cell fits either label without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Neon 50b board. The BMS accepted the cell without fault codes, charge termination triggered correctly at 4.2V, and the fuel gauge IC tracked state-of-charge without erratic jumps after the first full cycle.
- First-cycle fuel gauge calibration: After installation, disable fast charging for the first complete discharge-charge cycle. The fuel gauge IC on the Neon 50b is calibrated to the original cell's discharge curve. One slow cycle at standard current lets it recalibrate against the new cell before high-current charging begins.
Why the Neon 50b reports the wrong battery percentage after a cell swap
The Neon 50b uses a coulomb counter IC that builds its fuel gauge model from historical charge and discharge data on the original cell. When you swap the cell, that learned model no longer matches the new cell's actual voltage-to-capacity curve. The phone reads voltage and maps it to an outdated table, so the displayed percentage can read 40% while the cell is close to cutoff voltage. One full discharge down to automatic shutdown, followed by a complete uninterrupted charge to 100%, resets the coulomb counter's reference points against the new cell.
Sudden shutdown at 20–30% on the replacement cell
This happens when the cell voltage drops sharply under the combined load of the modem radio and screen — a voltage cliff the fuel gauge did not predict. The phone's OS still shows 20–30% because the coulomb counter hasn't been recalibrated to the new cell, but the actual cell voltage dips below the BMS cutoff threshold under load. The BMS protects the cell by triggering an immediate shutdown rather than allowing discharge below 3.0V. To resolve it, run one full discharge-to-shutdown cycle, then charge uninterrupted to 4.2V (100%) before normal use.